In recent years, a system for transmitting a signal by a radio wave between outside equipment and data carrier parts which are provided with an antenna element and a circuit element for storing data is being used in various fields. As data carrier parts, RF tag (signal frequency: 120 to 140 kHz (typically, 134.2 kHz)), a pen tag (signal frequency: 500 kHz) and noncontact IC card (signal frequency: 13.56-MHz band) are being put into practical use for management of various types of articles, physical distribution management, entering and leaving management, various types of tickets, a car-mounted keyless entry and immobilizer, various types of portable equipment such as portable telephones and the like.
And, a system of conducting the transmission of a signal with outside equipment by a radio wave is also used for the radio-controlled timepieces such as a wristwatch type radio-controlled timepiece, a stationary radio-controlled timepiece, and a car-mounted radio-controlled timepiece. Such a radio-controlled timepiece uses a signal carrier frequency of 40 to 120 kHz. For example, a signal carrier frequency of 40 kHz or 60 kHz is used in Japan and the United States, and a signal carrier frequency of 78 kHz is used in Europe. The radio-controlled timepiece is provided with an antenna element corresponding to such a signal carrier frequency.
For the antenna element of the data carrier parts, the radio-controlled timepieces and the like, an air-cored coil, or an inductive device (inductor) which combines a magnetic core and a coil is used. Among them, it is difficult to obtain inductance L and Q value (quality factor Q=ω•L/R (ω: angular frequency, L: inductance, R: resistance)) which are sufficiently used in a low frequency range of about a few hundred kHz or less by the air-cored coil. Therefore, the inductor element which has the magnetic core and the coil combined is mainly used for the antenna element which is used in a low frequency region (long-wave band).
Conventionally, it is general to use ferrite for the core of the antenna element, but the ferrite is brittle and has drawbacks that it is cracked if deformed only slightly and has a low magnetic permeability in terms of the magnetic characteristics. Therefore, the ferrite core cannot be used for the antenna element which is required to be thin and compact. Especially, the portable equipment is required to have shock resistance, so that its sufficient miniaturization cannot be achieved by using the ferrite which is easily cracked. The ferrite also has a disadvantage that a stable temperature characteristic cannot be obtained because it has a low Curie-point of about 200° C.
In connection with the circumstances described above, for example, Patent Documents 1 to 3 disclose that a multilayer body of amorphous magnetic alloy thin ribbons or nanocrystalline magnetic alloy thin ribbons is used for the magnetic core for antenna. But, the conventional antenna element, which is configured by winding a coil around the multilayer body (core) of the magnetic alloy thin ribbons, has not provided sufficient characteristics for compactness and high performance demanded to be achieved for the data carrier parts and radio-controlled timepieces.
For example, in a case where the antenna element is applied to portable equipment or the like, it is important that the antenna element is disposed within a limited space, so that it is sometimes necessary to dispose it in a bent state. But, for example, Patent Documents 2 and 3 cannot bend easily because the magnetic thin ribbons are mutually adhered with an insulating resin and the magnetic core has high rigidity. Even if the magnetic core can be bent, the characteristics of the magnetic alloy thin ribbons are degraded by a high stress produced when the magnetic core is bent. A magnetic core having a rectangular parallelepiped shape has a limited mounting style. Therefore, there are demands for a magnetic core of which characteristics are not degraded largely even if it is bent and an antenna element (inductor) using such a magnetic core.
To realize an essentially small and high-performance antenna element, it is important to further enhance the magnetic characteristics such as inductance L and Q value. The characteristics of the antenna element are influenced by not only the characteristics of the magnetic alloy thin ribbon but also its shape and size and the manufacturing conditions. But, an antenna element using a multilayer body (core) of existing magnetic alloy thin ribbons has not been studied enough about factors influencing on the characteristics when it is made compact and short. Therefore, characteristics (e.g., inductance L and Q value) conforming to the miniaturization and high performance which are demanded for the data carrier parts and radio-controlled timepieces have not been achieved.
Patent Document 3 discloses that induced magnetic anisotropy is provided to a magnetic alloy thin ribbon in its width direction. The magnetic alloy thin ribbon having the magnetic anisotropy provided in the width direction of the thin ribbon has characteristics (e.g., good Q value) which are demanded for an antenna element generally used in a relatively high frequency range, but the characteristics might become low depending on the used frequency region. Besides, Patent Document 3 discloses that magnetic alloy thin ribbons fabricated into a desired shape are stacked, and a heat treatment (heat treatment in a magnetic field) is performed while applying a magnetic field in the width direction of the thin ribbons, thereby providing induced magnetic anisotropy to the magnetic alloy thin ribbons in the width direction. But, when the width of the magnetic alloy thin ribbons is narrowed to realize the miniaturization of the antenna element, an influence of the demagnetizing field cannot be neglected, and there is a possibility that the characteristics of the antenna element are decreased.                Patent Document 1: Japanese Patent Laid-Open Application No. Hei 5-267922        Patent Document 2: Japanese Patent Laid-Open Application No. Hei 7-221533        Patent Document 3: Japanese Patent Laid-Open Application No. Hei 7-278763        